Unix Flashcards
(20 cards)
What is the first phase of the UNIX boot process?
BIOS - executes MBR
BIOS stands for Basic Input/Output System
What does MBR stand for in the UNIX boot process?
Master Boot Record
MBR is located in the first sector of the bootable disk
What is the role of GRUB in the UNIX boot process?
Grand Unified Boot Loader executes Kernel
GRUB provides a boot menu if there are multiple kernel images installed
What does the kernel do during the boot process?
Executes /sbin/init
The kernel mounts the root file system specified by the root= entry in grub.conf
What is the purpose of the init process?
Maintains the system in a specified run-level or state
Init process has process ID (PID) of 1
What is the default run-level in UNIX?
Runlevel 3
This run-level is typically for multi-user mode without GUI
What file contains the descriptions of different run states in UNIX?
/etc/inittab
The run levels include Halt, Single-user mode, Multi-user mode, and Full Multi-user mode
What does the command ‘ls’ do in UNIX?
Lists directory contents
Options include -a (all), -l (long listing format), and -R (recursive listing)
What does the ‘ps’ command report?
A snapshot of current processes
Options include -eF (standard syntax) and aux (every process in BSD syntax)
What is the function of the ‘grep’ command?
Searches for patterns in each file specified
Options include -v (invert match) and -i (ignore case)
What is iptables used for?
Administration tool for IPv4 packet filtering and NAT
It allows setting up and inspecting IP packet filter rules
What does the command ‘ifconfig’ do?
Used to configure the kernel-resident network interfaces
It is often deprecated in favor of the ‘ip’ command
What does the command ‘traceroute’ do?
Prints the route packets take to a network host
It tracks the route taken from an IP network to a given host
What does the ‘netstat’ command display?
Network connections, routing tables, interface statistics
Options include -a (active connections) and -v (verbose output)
What is a Shared Object in UNIX?
UNIX equivalent to Windows’ Dynamic Link Library (DLL)
It is intended to be shared by executable files
What information does the /etc/shadow file contain?
Password hashes for each user that has logged onto the machine
It is used for enhanced security of user passwords
What is the purpose of the .bashrc file?
Contains shell commands that change prompts, set environment variables, and define shell procedures
Bash reads and executes commands from ~/.bashrc
What does crontab command do in UNIX?
Opens the cron table for editing
The cron table lists tasks scheduled to run at regular time intervals
Fill in the blank: The system initialization script sends bootup messages to _______.
/var/log/boot.log
This log is generated by the boot script located at /etc/init.d/bootmisc.sh
True or False: The ‘iptables’ command can flush the selected chain.
True
The -F option in iptables is used to flush rules
